The Physiology Core will provide samples of myocardial tissue and isolated mitochondria for use by the individual projects. These samples are obtained from isolated, buffer perfused hearts in the baseline control state following ischemia and during ischemia and reperfusion. The use of a common core facility that performs isolated buffer-perfused heart preparations and isolates cardiac mitochondria will ensure that all projects utilize comparable experimental preparations. The core will facilitate the exchange of information among projects, since a common experimental heart model, perfusion technique, and method of mitochondrial isolation is used in each project. This approach will enhance the application of experimental results obtained by an individual project to experimental questions of interests to the other projects. The use of a core will also increase the sharing of tissue among projects will decrease animal use where appropriate, optimizing overall program efficiency. The core will also ensure that individual isolated heart preparations and mitochondrial isolates meet predefined control standards based upon our previous experimental work in this model. The core will interpret and make available the results of the isolated heart experiments to each investigator via a core-maintained database and program-wide network. Isolated mitochondria and heart tissue samples will be catalogued into a common database along with the physiologic results of the isolated heart experiments. Data results and tissue samples will be stored and maintained by the core, and will be released together to individual investigators as needed, allowing each project to easily integrate biochemical findings with pertinent physiologic results.